The below mentioned article provides a biology note on the mimicry in animals.
Imitating another is mimicry. The resemblances of an organism to another or even to an inanimate object in form, colour, attitude and action to escape notice of others or signalling apparent harmfulness or dangerous nature fall under mimicry.
Mimicry is probably the most effective adaptation for protection of animals. Mimicry may be passive or unconscious and active or conscious. Most of the mimics fall under passive category.
Protective mimicry has two aspects:
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a. Concealment and
b. Warning.
a. Concealment mimicry:
1. The smooth rounded form and texture of the crab, Cryptolithodes harmonize perfectly with the white quartz pebbles of the beach.
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2. The walking-stick insect, Carouse’s with its slender body, attenuated limbs, sympathetic colouration, slow movement often stiffening into rigidity, perfectly harmonizes with the twig on which it rests.
3. In walking-leaf insect Phylliun, the expanded body, flattened wings and appendages are green except for small, yellowish, irregular spots resembling the fungus that grows upon a dead leaf. It is a unique specimen in which resemblance is precise.
4. In the dead-leaf butterfly, Kallima paraleeta, the hind-wings elongate to resemble the stem on which it rests and also bear other leaf-like markings with extreme perfection. At rest, it perfectly resembles a dead and sere leaf in colour. The midrib, lateral ribs of leaf and black and mouldly spots also occur.
The wings bear striking recognition colouration above and the under surface has protective colouration. The recognition colouration, seen in flight, disappears on alighting, with the folding of the wings and the protective colour of the undersurface is exposed.
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Effectiveness of protective mimicry:
Protective mimicry is a successful tool for defence, only under certain conditions.
1. Both imitative and imitators must occur in the same area.
2. The imitators are more defenseless.
3. The imitators are always less in number in an area.
4. The imitation is always external.
b. Warning mimicry:
Mimicry of distasteful, dangerous and poisonous forms are considered warning mimicry.
1. Harmless snakes of different genera mimic the poisonous coral snakes in colouration and are immune from attack of other animals.
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2. The viceroy butterfly, Basilarchia archippus (= Limenitis disippus), which is palatable, protects itself from predators by mimicking inedible monarch butterfly Anasia plexippus (= Danais archippus).
Aggressive mimicry:
Mimicry which renders a predator invisible and helps to capture prey is aggressive mimicry.
1. The yellow bodies of certain carnivorous spiders harmonize with golden red and other flowers on which they rest. The insects visiting the flowers fail to detect them and become spider’s prey.
2. Spiders may resemble oak galls, droppings of^ birds and other forms and pounce upon unsuspected preys.
Simulation of death:
Feigning as a dead animal is a conscious mimicry.
1. Simulation of death is common in American opossums, Didelphis virginiana. Some believe that it is not actually feigning death, the animal faints in fright. However, the adaptation is of much importance for its survival.
2. Many hard-bodied beetles feign death and drop down like pebbles when they apprehend some danger.